Crossing the Streams
by Mendeia
Summary: Oneshot. Sometimes a new team needs a little input from some veterans...and sometimes they don't. Erin is out for a run when she makes an unusual friend with some very important advice for the newly-minted Ghostbuster.


So, I love the Ghostbusters. I loved the original movie, I LOVED The Real Ghostbusters cartoon, and I LOVED LOVED the new Ghostbusters this year. All in different ways and for different reasons – the various incarnations of the Ghostbusters have always seemed to be what I needed when I needed it most. So I figured maybe sometimes they need one another, too. Plus, how could I resist? Really?

Dedicated to my friend Peter Venkman on Twitter who has been a source of cheer all year long. Pete, I hope I continue to make you proud!

Enjoy!

* * *

Egon pushed his glasses up his nose. "I don't think we can really avoid it at this point."

"He's right," Ray said, half-smiling. "Our quantum universe is unstable enough as it is with all the world-hopping, ectoplasmic infusions, and dimensional cross-rips. The last thing we need right now is for a parallel world to go down."

"Will it really fall apart?" Winston asked. "I mean...aren't there worlds without us in them?"

"Hundreds of trillions at least," Egon said. "But this one is, for lack of a better way of explaining it, nested quite close to us. It's a dimensional neighbor."

"And when your neighbor's plumbing bursts, you have a really bad day too," Ray finished.

Across the room, Peter sighed. "Okay. _Fine_. You've convinced me. I'll go." But he looked up with a smirk. "Do I get to wear a disguise?"

-==OOO==-

Erin had never been the most athletic of girls in high school, but taking up running had saved her sanity in college by giving her the chance to get away. To run and lose herself in the rhythm of her body moving forward, the blissful quiet of her mind taken up with nothing but stop-lights and sidewalks. To forget, for a moment, about everything.

About the professors who graded her more harshly when she didn't wear skirts to class.

About the students who stared at her when she was the only woman in the room.

About the administrators who overtly supported her thesis, but managed to _forget_ to allocate her any resources or lab-space for her work.

About the fight with Abby and the loss of her best friend.

But that had all changed within the last year. Now Erin was a Ghostbuster right alongside Abby. And while the DHS was doing its best to quell public knowledge of their work – and good luck with that, they were YouTube rockstars now and probably forever – she wasn't an outsider anymore. She wasn't the strange "ghost girl," or even the strange "physics chick."

Or, at least, if she _was_ strange, well, she wasn't alone in it anymore.

And besides. Holtzmann was _way_ stranger. _Orders of magnitude_ stranger.

Erin wondered if Holtzmann was even aware that her innate weirdness was like a blind for her and Abby and even Patty. That when Holtzmann was being profoundly Holtzmann-y in front of the DHS or the cameras or the cops, nobody remembered or even noticed that the rest of this team was a little odd, too. Compared to Holtzmann, they were downright boring.

She suspected that Holtzmann did know. That, just as Erin had thrown herself into a portal to save her friend, Holtzmann threw herself and all her innate oddness into the public eye every chance she got as a different kind of shield. A different way of saving them.

 _And because it's fun. Don't forget that it's fun._

Erin snorted and almost lost her rhythm.

 _Now I'm hearing Holtzmann in my head. Either my subconscious is getting a little stranger, too, or that equipment is more psychoactive than we thought._

 _Or both._

Erin abruptly turned off the sidewalk into Battery Park.

She had returned to running not long after defeating Rowan, and she was almost back to the endurance she had enjoyed a decade before. She had never really fallen out of shape, but there was a difference between being able to run the length of Manhattan and being able to run it in an emergency with a pack on her back. She had been planning on challenging Patty to a race across Central Park one of these days just to prove to herself that she could win it.

Prove to herself that she had something to contribute, that she belonged, even if she wasn't as strong as Patty or zany as Holtzmann or comfortable with this whole gig as Abby.

But maybe it didn't matter anymore.

Erin stopped beside Hope Garden and drew off to one side of the path so she could roll her shoulders and neck while keeping her feet moving.

In the comparative quiet of the park, the crinkling from her shoe was more audible.

Erin reached down to pull the piece of paper out of where she had tucked it inside her running shoe, cursing for the millionth time the lack of pockets in women's' athletic gear. The paper was newly wrinkled and had certainly taken on the damp and smell of her well-used shoe, but it was just as intriguing as it had been an hour ago.

" _Doctor Erin Gilbert,_

 _In light of your excellent work and your dedication to the study of physics, we would like to extend an invitation to you to visit our facility at Joint Base Anacostia–Bolling, Washington DC…"_

Erin folded it up again, creasing the paper over the Defense Intelligence Agency official seal.

She knew what the letter really meant. What it really wanted.

 _Invitation. Sure._

 _Followed by a job-offer._

 _Followed by all the funding and equipment I could ever want. And practical applications that could be utilized worldwide._

It was perfect. Fantastic. Unbelievable.

So of course it came with a catch.

 _"...However, due to the sensitive nature of our work and the known affiliations of your current partners, we ask you to refrain from extending this offer to them."_

 _Translation: this ticket is only for one._

Normally Erin would have balled up the letter at once and thrown it aside. Or maybe let Holtzmann set it on fire. Or let Abby use it for target-practice. Or let Patty put it through her ghost chipper. Or let Kevin do whatever he did with the rest of the junk mail, though Erin had a suspicion he was just hiding it in the fish tank he'd stolen from their first office and installed next to his new desk.

Go without the rest of the team? No way! They were friends! Family!

Except…

 _What if I could help people? What if there's some other ghost girl out there scared of the thing at the end of her bed? We can really only protect the people in the city right now. How many other ghosts are out there? How many other ways people could be hurt?_

 _Don't I have some obligation to them, too?_

 _Abby and Holtz and Patty would protect New York. I could...I could help the government put a Ghostbuster in every city. I could help so many people._

 _However..._

She was so caught up in her thoughts, she missed the person who came up from behind, snatched the letter from her hands, and started to run away with it.

"Hey!"

Erin had to shuffle her shoe back on before she could take off after the thief. Thankfully, he was fairly easy to spot in a brown jumpsuit with a teal collar. But on his back…

 _Another pack? But not like ours._

 _Another Rowan? Please not another Rowan._

Erin put on a burst of speed and caught up to the man in a few long strides. She was certain she her knees were going to regret it, but she tackled him anyway, bringing him rolling to the damp ground.

He squeaked. "Oof! Hey! That was just rude!"

"Seriously? You're going with 'rude' when you just stole something from me?" Erin snatched back her letter and jumped off, quick to put distance between herself and someone who was armed. And if her shins had been scraped across the ground and her elbow was torn open a little, at least she hadn't missed. A flying mid-air tackle that missed would be _really_ hard to explain to the others.

But he didn't bother to get up, instead peering up at her with big green eyes and a half-detached, obviously-false, _enormous_ handlebar mustache. "Well, yeah. But I just wanted to talk to you and you were all off in la-la land, so…"

Erin took a deep breath. "So...what? Are you a fan? 'Cause I don't do autographs on any body part of yours no matter _how_ big it is."

" _Ew_!" He flinched and screwed up his face. "That's gross!" Then, "Do people actually ask you that?"

"When they're not telling me I should unzip my jumpsuit more or...you know what? Never mind."

"I'm Peter." He smiled and got to his feet, pulling off the mustache after a moment. "And I'm not going to ask you anything like that. Okay?"

"Doctor Erin Gilbert." Erin peered at him. "If you're doing a gender-swap cosplay, our jumpsuits are really more of a tan than brown and they have orange stripes."

Peter snorted. "Not even close! Wait, yours are all the same? Isn't it boring?"

Erin blinked.

Peter ran a hand through his unruly brown hair. "Okay. Let's start over." He grinned brightly. "Hi! I'm Peter Venkman and I'm a Ghostbuster from a parallel universe."

"Okay, I guess we can do it that way." Erin sighed. Then she made a too-bright face common to preschool teachers. "Hi Peter! I'm Erin!"

Peter pouted. "You're not taking me seriously."

"Not even a little."

"I should have made Ray do this." Peter folded his arms over his chest. "He owes me a month of chores for this."

Erin started to edge sideways. "So, if that's all, I guess…"

"You got a letter to leave the Ghostbusters."

She froze. "You read it?"

"I didn't even look at it," Peter replied. "It was all sweaty and stuck together and I was kinda running away from you." He smirked. "But I was serious about that alternate dimension thing."

Erin wanted to shove the letter out of sight – but again with the no pockets and she didn't want to take off her shoe again if this went sideways. _That's it. I'm buying men's running pants from now on._

"Look," Peter said, holding up both hands as if in surrender. "I don't care if you believe me or not. I just want you to really think about what you'd be losing if you left your team. Even if you're not the greatest at all the science stuff -"

"I'm a top-notch particle physicist," she interrupted.

"Really? Cool!" Peter grinned again. "I've never been as good at that stuff. But, anyway. The point is that they need you. You can't just leave them."

Erin rolled her eyes. "I was never _going_ to leave them."

"Right, because you're teammates!"

"Well, that. _And_ because the DHS already told me it's just some Washington politics being played and we're their newest pawn. The invite is more or less bogus. I mean, don't get me wrong, it would be great if we could consult with more than just the mayor and start making an impact, but that's not happening any time soon. But even if it _did_ happen, there's no way I'd go without the others."

Peter blinked. "Uh...you sure?"

"Yeah." Erin nodded and put her hands on her hips. "Was that all you wanted?"

Peter frowned. "Wait. So...you're not leaving the team?"

"Nope."

"Huh." Peter ran a hand through his hair again. "But...Egon was so sure there was something that was...what'd he say? Threatening the integrity of the Ghostbusters? Something like that. If it's not you, who is it?"

Erin shrugged. "Maybe your friend's wrong."

"Egon's _never_ wrong."

Peter said it with such certainty, such loyalty, Erin had to smile. Abby had defended Erin that exact way many times. As Erin had defended her. As Patty defended them both. As they all defended Holtzmann even when things went wildly bizarre. Or exploded.

"Well, tell him to check his math, I guess." Then, just in case, "And if he really is trying to track the source of a timeline disruption in another dimension, remind him that Planck's Constant also suffers from dimensional relativity so he can't solve for it without adjusting for the differing quantum realities."

Peter looked at her with the expression she had seen many times in her students.

"Uh...would you maybe mind writing that down?"

-==OOO==-

"Hey! How was the run?"

Erin was pulled away from watching Kevin pretending to type by Abby's voice, coming from where she had set up an office behind his desk. It was, in theory, supposed to be a conference room and a place to talk to potential clients. In practice, it served as the actual receptionist station and they all took turns rotating through it while Kevin worked on remembering how his job worked.

"Pretty good," she said, moving past Kevin – and wiggling a little in the hope he would turn and see something he liked – and heading in through the open door. Abby was marking up the big whiteboard calendar for the next week of work and it was filled with a lot of clients in green; meetings with the DHS went in red and stay-away-because-Holtzmann's-doing-something-dangerous-again was in purple.

"Hey."

Erin tried to pretend she didn't see that expression on Abby's face.

"What?"

"You look like you had a little... _fun_." Abby pursed her lips, fighting a smile. "Meet someone new?"

"What makes you say that?"

"Grass stains, mussed hair, and what looks like a phone number sticking out of your bra."

Erin yanked the paper from where it was peeking out of her tank top. "Look, that's not a phone number. It's an equation. I was trying to help reconcile the quantum of action for…"

"Yeah, it _looks_ like there was some 'action' involved."

Erin wanted to feign indignance but instead she laughed. "Really. He was either a cosplayer or an actual inter-dimensional Ghostbuster. Kinda hard to tell."

Now Abby glared at her. "You should've brought him back here! If he was the real deal, we should have gotten the chance to study him! Did you at least get a skin sample?"

"Absolutely I did not."

Abby sighed. "And if he'd been a cosplayer, Kevin would have loved it."

"I know." Erin was genuinely regretful about that part. "But he said the inter-dimensional window was limited. Or, I dunno, maybe his Uber arrived. Anyway." She rubbed a hand against her elbow, flicking off some dirt and grass still stubbornly left behind from her tackle. "I need a shower."

"Well, stay out of Holtzmann's lab when you go up. She's been cackling all morning."

"Yeah, I'll do that."

Erin was halfway up the stairs to the second level when there was the familiar sound of a door banging open and then Holtzmann stood at the landing outside her lab leaning out over the first floor. She was half-covered with either slime or glue – either was equally possible at this point – and her goggles were still smoking.

"Guess who's got two thumbs and an invite to join the North Korean space program!" She cocked both thumbs in her direction. "Me!"

-==OOO==-

"Ha!" Peter laughed. "That makes it _your_ turn! I already talked to mine!"

Egon buried his face in both hands and wondered if it was too late to dismantle their own Ghostbusters instead.

-==OOO==-

The End


End file.
